A fluorosulfonylimide salt and a derivative thereof are useful for various use applications such as an electrolyte of various power storage devices, an additive, a selective electrophilic fluorinating agent, a photo-acid-generating agent, a heat-acid-generating agent and a near-infrared light-absorbing pigment.
Patent Document 1 discloses a method for producing a highly pure disulfonylamine alkali metal salt by subjecting a disulfonylamine onium salt to a cation exchange reaction in an organic solvent, filtering the thus obtained organic solvent solution of an alkali metal salt with a filter having a retained particle diameter of 0.1 to 10 μm, concentrating the filtrate, and crystalizing the disulfonylamine alkali metal salt.